Public voice communication technology has undergone a considerable development since Bell has invented the telephone. Now there are two major public voice communication technologies, one of which is a normal telephone that is a circuit-switched wired public telephone network (such as PSTN, ISDN and so on) or a wireless telephone network that is the most traditional fixed telephone or wireless telephone, and the other is the recently rapidly developing network telephone based on the packet switching technology that is VoIP telephone. The two telephone technologies have their advantages and disadvantages respectively, wherein, the PSTN and the wireless telephone have clear voice, and they can provide the most comprehensive range of services, such as a variety of public services telephones, emergency calls, dialing a call without commercial power; however costs are usually high especially for cross-regional and cross-border long distance calls. While calling costs may be substantially reduced when the VoIP telephone using free internet technology is utilized, especially the network terminal-to-network terminal calls are usually free. However, because of the inherent delay defect of the packet switching technology to which the voice communication is sensitive, the voice quality may be reduced inevitably. Moreover, the VoIP telephone generally can not provide emergency calls and people can not dial a call without commercial power. With the increasing popularity of computer, the personal computer has become a necessary equipment of many families or person. Meanwhile, in most cases, a PSTN phone will also be equipped which usually may take up the additional desktop space.